The invention relates to haematological analysers designed to automatically analyse samples of blood products.
It relates particularly to a device for processing samples of blood products contained in tubes closed by means of bungs and loaded into cassettes, and incorporating means of agitation capable of agitating the tubes, together with means of sampling capable of collecting at least one sample from a pre-agitated tube.
Such devices are designed to agitate the tube in order to mix the constituents of the blood product which it contains, and to then take a sample having a composition that is both homogeneous and representative of the blood product to be analysed.
In particular an automatic device is known, according to U.S. Pat. No. 3,231,244 for the mixing of blood products which includes a rotary drum incorporating slots designed to hold tubes containing such products. The tubes are arranged radially relative to the axis of rotation of the drum, so that their respective bungs are directed outward. In fact, this is only an agitation device which has the drawback that the tubes have to be loaded manually onto the drum, then removed manually from the drum once the agitation process has been completed.
Also, a device is known according to EP-A-0 061 317 for the agitation and sampling of specimens of blood products, wherein the tubes containing the products are grouped in cassettes which are placed manually in a rotary drum. The purpose of the latter is to mix the blood products by rotation and to immobilise a cassette in an essentially vertical position so that tubes it contains are held with their bungs facing downward. A sampling station is provided to draw a sample from a tube in a cassette after piercing the tube bung. After analysis, the cassettes are manually removed from the drum.
The principal drawback of this known device is that it is incapable of rotating the drum, thereby agitating the set of tubes, during the sampling operation itself.
A device is also known, according to FR-A-2 730 315, for the agitation and sampling of specimens of blood products from tubes grouped in cassettes. This known device includes a cassette holder designed to support and agitate at least one cassette loaded with at least one tube, together with at least one sampling station designed to pierce the tube bung and draw off the specimen. By virtue of the fact that the sample is taken from a tube, away from the cassette, there is no necessity to provide means of locking the holder to prevent rotation during the sampling operation.
This known device is mechanically very complex, reflected in its unduly high cost.
A further device is known, according to FR-A-2 692 358, for the transfer, agitation and sampling of blood product specimens which includes a mobile carriage designed to remove a cassette loaded with specimen tubes from a storage receptacle and to transfer the cassette to a rotary carriage. The latter agitates the specimens and can be immobilised to allow samples to be collected from the cassette tubes by means of a sampling station.
This devices presents essentially the same shortcomings as those cited previously.
The aim of the invention disclosed is notably to overcome the aforementioned shortcomings.
In particular, the invention proposes a device for processing samples of blood products contained in tubes loaded into cassettes, whereby agitation of the tubes is performed independently of the cassettes, which avoids having to agitate the cassettes themselves.
The invention also aims to provide such a processing device which facilitates agitation of a tube independently of the cassette, and then enables a specimen of blood products to be collected from the tube after it has been replaced in the cassette.
The invention also aims to provide a device as described above, wherein the cassettes present a range of different loading or unloading options for the tubes.
The invention also aims to provide such a device that can be readily integrated into a line of several blood analysis units.
To this end, the invention proposes a processing device of the type defined in the introduction, which includes means of transfer designed to move the cassettes individually on a pre-determined path, and in which the means of agitation incorporate at least one pick-up mechanism designed to pick up at least one selected tube from a cassette immobilised on the path, to remove said tube from the cassette, to agitate the tube and to replace it in the cassette, and in which the sampling means include at least one needle designed to draw a given sample quantity from the tube that has been pre-agitated and replaced in the cassette.
Thus, the device according to the invention agitates the tubes after they have been removed from the cassette, and draws samples from the tubes which, following agitation, have been replaced in the cassette.
Consequently, this avoids the necessity of agitating the entire cassette as in the majority of the devices according to the previous state of the art.
This has the further advantage that the cassettes can be moved along a chosen path, in particular a linear path, thereby facilitating integration of the invention into a line of haematological analysis units.
In addition, by virtue of the fact that loading and unloading of the tubes is performed by means of a cassette, which is moved by transfer means, these operations can be carried out in different ways, in particular via the top and via the side of the cassette.
Furthermore, by virtue of the fact that the means of agitation are applied to one or more tubes, and not to a cassette, the overall dimensions of the device are reduced, which contributes to its ease of integration into a line of several units.
In a preferred embodiment, the means of transfer include a carriage capable of being attached to a cassette via a retractable finger, and means of transfer capable of moving the carriage between defined positions on the path.
According to another characteristic of the invention, the tubes are placed vertically in the cassette and in line with the direction of travel, whilst the means of agitation are arranged to withdraw at least one tube laterally from the cassette and to replace it laterally into the cassette after agitation.
Advantageously, the cassette incorporates flexible U-clips allowing the removal and replacement of a tube by a lateral movement parallel to itself or by an axial movement of the tube along the axis of the latter.
The resultant advantage is that the tubes can be loaded or unloaded either via the side of the cassette or via the top of the cassette.
According to another characteristic of the invention, the pick-up mechanism or each such mechanism is capable of being driven in continuous rotation by a motor, thereby effecting continuous agitation by turning the tube through a complete revolution.
In a preferred embodiment, the means of agitation incorporate a mobile head carrying the pick-up mechanism(s) and which is capable of being driven in translational or rotational motion by means of a coupling arrangement connected to a motor with two directions of rotation.
Advantageously, this coupling arrangement includes a screw and nut and is capable of being driven in rotation by the motor in a selective manner, operating the screw either to move the mobile head away from the cassette or to bring the mobile head closer to the cassette, the mobile head in this case being prevented from rotating and fixed in a selected orientation by locking means set in a locking position.
Provision is made advantageously for these locking means to be additionally set in a release position when the coupling arrangement has arrived at a stop position at the end of the screw-in motion, thereby enabling a rotational movement of the mobile head to agitate the tube or tubes.
Preferably, the rotational movement of the mobile head is a continuous and complete rotation in the direction of the screw-in action of the coupling arrangement.
According to another characteristic of the invention, the device includes an arrangement for opening and closing the pick-up mechanism which is capable of being actuated in a translational motion by the coupling arrangement once the latter has arrived at a stop position at the end of the screw-out motion, with the mobile head being prevented from rotating by the locking means.
Advantageously, the pick-up mechanism includes two clamp elements, each of which has at least one jaw and defines a cam groove, together with a resilient return device connecting the two clamp elements to bring the jaws towards each other, the opening and closing mechanism incorporating cam fingers moved by the coupling arrangement and cooperating respectively with the cam grooves.
According to another characteristic of the invention, the device includes a means of manual loading, also referred to as the emergency loading station, placed in proximity to the transfer means and designed to hold at least one tube and to place this tube in the path of the transfer means and sampling means, when no cassette is present, to enable the collection of a sample by the sampling means.
This means of manual loading advantageously includes a rotating and tilting head having indexed positions and incorporating slots designed to accommodate tubes of different sizes.
According to a further characteristic of the invention, the sampling means include a carriage supporting a piercing device and sampling needle, and this carriage is movable between a sampling position, at which the piercing device pierces the tube bung and the sampling needle draws off a total specimen quantity, and at least one distribution position at which the sampling needle expels the said total specimen quantity, or part thereof, into a receptacle such as a reagent vessel.
Advantageously, the device additionally includes a cassette loading station and a cassette unloading station placed respectively upstream and downstream of the transfer means.